Loop-Antenna RF Tag With Metal Cover for Shielding Constraints
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Solution Overview
Problem
Conventional RFID tags with dipole antennas face size constraints and communication limitations when housed in metal protective casings, as the metal casing shields the auxiliary antenna, preventing effective radiocommunication.
Innovation Solution
An RFID tag design where the inlay with a loop circuit antenna is housed in a casing with a metal top cover acting as an auxiliary antenna, allowing for improved communication characteristics without the constraints of the dipole antenna length, enabling size reduction and enhanced radiocommunication.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the inlay is accommodated in a metal protective casing, then the inlay is protected from physical and mechanical shocks, but the metal casing shields the antenna and prevents effective radiocommunication
Solution Approach 1:
The protective casing is divided into two parts: a non-conductive base casing and a separate conductive top cover. The base casing provides mechanical protection while the removable top cover can be detached to allow radiocommunication when needed, thus segmenting the protective function from the electromagnetic shielding function.
Solution Approach 2:
The top cover is designed to be movable relative to the base casing, allowing it to be removed or positioned to expose the antenna. This dynamic configuration enables the system to switch between protected state and communicative state, resolving the contradiction between protection and radiocommunication effectiveness.
2Reliability
If a dipole antenna is used in the inlay, then radiocommunication is achieved, but the antenna length constrains the size reduction of the RF tag
Solution Approach 1:
The conductive top cover serves dual functions: it acts as part of the antenna system for radiocommunication and simultaneously serves as the protective cover for the inlay. This merging of functions eliminates the need for a separate dipole antenna structure, enabling size reduction while maintaining communication capability.
Solution Approach 2:
The top cover is designed to perform multiple functions: electromagnetic radiation/ reception as an antenna element, mechanical protection of the inlay, and structural closure of the casing. This multi-functionality reduces the overall component count and enables compact design without sacrificing communication performance.
3Adaptability or versatility
If the inlay is made small and thin for easy mounting, then mounting flexibility is improved, but the inlay becomes vulnerable to physical and mechanical damage
Solution Approach 1:
The thin and small inlay is nested within the protective casing structure, which provides mechanical strength and protection. The inlay maintains its compact form factor for easy mounting while the surrounding casing absorbs physical and mechanical stresses, protecting the vulnerable inlay components.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution enables effective radiocommunication over extended distances while protecting the inlay from physical forces, allowing for size reduction and increased design flexibility of the RFID tag.
Implementation Method 1
the top cover (20) to be disposed on at least one surface (top surface) of the casing (50) functions as an antenna of the inlay (10)
Implementation Method 2
an electronic circuit having the IC chip and a radio antenna is sealed and coated with a substrate such as a resin film
Data Source
Figure 1(a)~1(b)
Figure 2
Figure 3
AI summary
The present invention improves the communication characteristics of an inlay using an auxiliary antenna, while protecting the inlay from physical and mechanical external forces, shocks or the like, without being subjected to the constraints of a dipole antenna. To that end, the present invention has a configuration, comprising: an inlay 10 comprising an IC chip 11 and only a loop circuit antenna 12, on which the IC chip 11 is mounted, and not comprising another antenna; a casing 50 for accommodating the inlay 10 therein; and a planar top cover 20 covering one surface side of the casing 50. The top cover 20 is formed of a prescribed metallic material and comprises a cutout 21 opening at least on one side. The inlay 10 is disposed in the casing 50 so as to be positioned inside the cutout 21. The top cover 20 functions as an antenna of the inlay 10 by being electrically connected to the inlay 10.